1. Field of the Invention
The present invention relates to a brushless generator with permanent magnets. It specifically relates to a kind of brushless generator that, after generating and rectifying voltage using permanent magnets and windings of an auxiliary generator, it supplies current to an exciter of a main generator, and hence, generates electricity,
2. Description of the Related Art
FIG. 1 is a conceptual diagram of an exciter of a conventional brushless generator and is a drawing regarding an AC (alternating Current) exciter. The AC exciter is comprised of an armature 26, which is made of armature windings 24 and an armature magnetic core 25, and a field system 29, which is made of a field winding 27 and a field magnetic core 28.
In the conventional AC exciter comprised of as described above, field magnetic flux 31 is generated from the static field system 29, and when the armature 26 rotates, voltage gets induced into the rotating armature windings 24 because magnetic flux interlinkage from the armature windings 24 changes periodically.
FIG. 2 is a circuit diagram of the conventional brushless generator with the AC exciter comprised of as described above. As shown in FIG. 2, the generator is comprised of an AC exciter 30, which is made of the armature windings 24 and the field winding 27, semiconductor rectifiers 32, which is connected to each terminal of the armature windings 24, and a main generator 36, which is made of a field winding 34 and armature windings 35. Unexplained reference numeral 33 represents a rotor that is comprised of an armature 26 of the AC exciter 30, semiconductor rectifiers 32, and a field winding 34 of the main generator.
According to FIGS. 1 and 2, if the field magnetic flux 31 is generated from the field system 29 and the rotor 33 is rotated, then voltage gets induced in the armature windings 24 of the rotating AC exciter 30. After the induced voltage is converted into direct current (DC) via the semiconductor rectifiers 32, the direct current is supplied to the field winding 34 of the main generator 36. Therefore, the voltage gets induced in the stationary armature windings 35 of the main generator 36. As a result, it is possible to generate electricity without a brush.
However, the conventional brushless generator as described above has a disadvantage of the large capacity of a power supply device that supplies power to the field winding 27, because the field magnetic flux 31 is generated from the field system 29 of the AC exciter. Also, the conventional brushless generator has another disadvantage that is its inability of self-generation of electricity, and it is because it needs external power when the generator is re-operating from a suspension state.
Especially, in the case where there exists a need for lightweight of a generator and a power supply without external power source but with only mechanical power, such as in airplanes, cargo planes and etc, the difficulty arises with the conventional brushless generator.